Question

Give the IUPAC name for $C{H_3} - C{H_2} - C{H_2} - OH$ .
A. Propanal
B. Propanol
C. Propionic acid
D. Propane

Answer 1

IUPAC refers to the International Union of Pure and Applied Chemistry. It gives a unique method for systematic naming of organic compounds.

Complete answer:
IUPAC naming of organic compounds follows specific rules which depend on the nature of the compound. The rule gives systematic names for a variety of compounds according to the functional group present.
Rules for naming organic compounds given by IUPAC are as follows:
a. The parent chain has to be identified first which contains the longest chain of hydrocarbons.
b. The primary functional group has to be determined.
c. The numbering of carbon starts from the carbon which is attached to the main functional group.
The given compound is an alcohol organic compound. The nomenclature of alcohol follows the above rules. The primary functional group is the hydroxyl group in the given compound which is attached to an alkane chain. The alkyl chain is a propyl group.
The numbering of carbon atoms starts from the carbon which is attached to the hydroxyl functional group so that the functional group gets the lowest number. The alkane chain is written followed by –ol as suffix.

Thus the IUPAC name of the given compound is propan-$1$-ol, i.e. option B is the correct answer.
Propanal is an organic compound which contains an aldehyde functional group. Propionic acid is an organic compound which contains a carboxylic acid functional group. Propane is a hydrocarbon containing three carbon chains.

Hence, option B is the correct answer.

Note: In some cases the alcohols are also named by a prefix as hydroxyl. But in these cases another functional group is present which is added in the suffix. For example $2$-hydroxyacetaldehyde contains two functional groups which are an aldehyde and an alcohol. The aldehyde is favored over the alcohol for numbering of carbon atoms.